Within the oil & gas industry, it is very important to accurately gauge the quality of casings. The industry currently employs various methods for the verification of the quality of the casing. Typically, calipers or cameras are employed to determine whether the casing/tubing is cylindrical and or not-corroded. However, cameras require the wellbore to contain optically clear fluids; otherwise, they are incapable of distinguishing features within the fluid/borehole. More recently, ultrasonic tools are run within the well in an attempt to image the casing/tubing, or elements outside of the tubing, such as the parts of a downhole safety valve. However, ultrasonic tools are model dependent, so prior knowledge of the precise makeup and status of the well is typically required for the ultrasound data to be compared against.
No viable technologies are currently available which use a method or means to employ a combination of collimators, located cylindrically around an X-ray source, located within a non-padded concentrically-located borehole logging tool, together with a single or plurality of rotatable two dimensional per-pixel collimated imaging detector array(s) to also be used as the primary imaging detector(s), to produce complete backscatter images of the casing/tubing.
Prior art teaches a variety of techniques that use x-rays or other radiant energy to inspect or obtain information about the structures within or surrounding the borehole of a water, oil or gas well, yet none teach a method or system to use first order detectors (which are typically used to compensate for mud-cake/fluid variations) to create a photograph-like image of the casing itself.
U.S. Pat. No. 7,675,029 to Teague et al. teaches an apparatus wherein the measurement of x-ray backscattered photons from any horizontal surface inside of a borehole admits to two-dimensional imaging techniques.
U.S. Pat. No. 8,481,919 to Teague teaches a method of producing Compton-spectrum radiation in a borehole without the use of radioactive isotopes. The reference further teaches rotating collimators around a fixed source installed internally to the apparatus but does not have solid-state detectors with collimators. It further teaches the use of conical and radially symmetrical anode arrangements to permit the production of panoramic x-ray radiation.
U.S. Pat. No. 7,705,294 to Teague teaches an apparatus that measures backscattered x-rays from the inner layers of a borehole in selected radial directions, with the missing segment data being populated through movement of the apparatus through the borehole. The apparatus permits generation of data for a two-dimensional reconstruction of the well or borehole, but the publication does not disclose the necessary geometry for the illuminating x-ray beam to permit discrimination of the depth from which the backscattered photons originated, rather, only the direction.
U.S. Pat. No. 3,564,251 to Youmans discloses the use of a azimuthally scanning collimated x-ray beam to produce an attenuated signal at a detector for the purposes of producing a spiral-formed log of the inside of a casing or borehole surface immediately surrounding the tool, effectively embodied as an x-ray caliper. However, the reference fails to teach or suggest a means or method to create a photo-like image, other than a two-dimensional radial plot on an oscilloscope.
U.S. Pat. No. 7,634,059 to Wraight discloses an apparatus that may be used to produce individual two-dimensional x-ray images of the inner surface inside of a borehole using a single pin-hole camera without the technical possibility to ascertain the azimuth of the image being taken, so that a tessellation/stitching of multiple images is also not disclosed.
US2013/0009049 by Smaardyk discloses an apparatus that allows measurement of backscattered x-rays from the inner layers of a borehole. However, the reference fails to disclose a means or method to create photo-like two dimensional images of the inner surfaces of the casing while the tool is being axially moved (‘logged’) through the wellbore so that a consolidated two-dimensional image of the well casing can be produced.
U.S. Pat. No. 8,138,471 to Shedlock discloses provides a scanning-beam apparatus based on an x-ray source, a rotatable x-ray beam collimator, and solid-state radiation detectors enabling the imaging of only the inner surfaces of borehole casings and pipelines. However, the reference fails to disclose a means or method to create photo-like two dimensional images of the inner surfaces of the casing while the tool is being axially moved (‘logged’) through the wellbore so that a consolidated two-dimensional image of the well casing can be produced.
U.S. Pat. No. 5,326,970 to Bayless discloses a tool that attempts to measure backscattered x-rays azimuthally in a single direction in order to measure formation density, with the x-ray source being based on a linear accelerator. However, the reference fails to teach a means or method to create photo-like two dimensional images of the inner surfaces of the casing while the tool is being axially moved (‘logged’) through the wellbore so that a consolidated two-dimensional image of the well casing can be produced. It also fails to teach or suggest a method and means that uses a fixed conical/panoramic beam to illuminate the well casing, whereas the directional collimation is located at the rotating detector.
U.S. Pat. No. 5,081,611 to Hornby discloses a method of back projection to determine acoustic physical parameters of the earth formation longitudinally along the borehole using a single ultrasonic transducer and a number of receivers, which are distributed along the primary axis of the tool.
U.S. Pat. No. 6,725,161 to Hillis discloses a method of placing a transmitter in a borehole and a receiver on the surface of the earth, or a receiver in a borehole and a transmitter on the surface of the earth, with the aim to determine structural information regarding the geological materials between the transmitter and receiver.
U.S. Pat. No. 6,876,721 to Siddiqui discloses a method to correlate information taken from a core-sample with information from a borehole density log. The core-sample information is derived from a CT scan of the core-sample, whereby the x-ray source and detectors are located on the outside of the sample, and thereby configured as an outside-looking-in arrangement. Various kinds of information from the CT scan such as its bulk density is compared to and correlated with the log information.
U.S. Pat. No. 4,464,569 to Flaum discloses a method to determine the elemental composition of earth formations surrounding a well borehole by processing the detected neutron capture gamma radiation emanating from the earth formation after neutron irradiation of the earth formation by a neutron spectroscopy logging tool.
U.S. Pat. No. 4,433,240 to Seeman discloses a borehole logging tool that detects natural radiation from the rock of the formation and logs said information so that it may be represented in an intensity versus depth plot format.
U.S. Pat. No. 3,976,879 to Turcotte discloses a borehole logging tool that detects and records the backscattered radiation from the formation surrounding the borehole by means of a pulsed electromagnetic energy or photon source, so that characteristic information may be represented in an intensity versus depth plot format.
U.S. Pat. No. 8,664,587 to Evans et al. discloses a method and means for creating azimuthal neutron porosity images in a logging while drilling environment. Since bottom hole assembly based systems historically relied upon the rotation of the drill string to assist in the acquisition of azimuthally dependent data, the reference discusses an arrangement of azimuthally static detectors which could be implemented in a modem BHA that does not necessarily rotate with the bit, by subdividing the neutron detectors into a plurality of azimuthally arranged detectors which are shielded within a moderator to infer directionality to incident neutrons and gamma.
U.S. Pat. No. 9,012,836 to Wilson et al. discloses a method and means for creating azimuthal neutron porosity images in a wireline environment. Similar to U.S. Pat. No. 8,664,587, the reference discusses an arrangement of azimuthally static detectors which could be implemented in a wireline tool to assist an operator in interpreting logs post-fracking by subdividing the neutron detectors into a plurality of azimuthally arranged detectors, which are in turn shielded within a moderator to infer directionality to incident neutrons and gamma.
U.S. Pat. No. 4,883,956 to Manente et al. discloses an apparatus and method for investigation of subsurface earth formations, in particular using an apparatus adapted for movement through a borehole. Depending upon the formation characteristic or characteristics to be measured, the apparatus may include a natural or artificial radiation source for irradiating the formations with penetrating radiation such as gamma rays, x-rays or neutrons. The light produced by a scintillator in response to detected radiation is used to generate a signal representative of at least one characteristic of the radiation and that signal is recorded.
U.S. Pat. No. 6,078,867 to Plumb discloses a method for generating a three-dimensional graphical representation of a borehole, comprising the steps of: receiving caliper data relating to the borehole, generating a three-dimensional wire mesh model of the borehole from the caliper data, and color mapping the three-dimensional wire mesh model from the caliper data based on either borehole form, rugosity and/or lithology.